过渡金属Hf_3^(2-)团簇的双重芳香性(σ与π)的理论研究

Theoretical study on the two-fold aromaticity of all-metallic clusters Hf_3^(2-)

我们将芳香性概念扩展到第四副族元素铪组成的金属团簇Hf_3^(2-).运用两种密度泛函理论(B3LYP, B3PW91)和从头算方法MP2,对金属团簇Hf_3^(2-)的稳定结构与电子总能量(考虑了零点能ZPE)作了理论计算.计算的结果显示,在金属团簇Hf_3^(2-)的D_(3h)平面结构是最稳定的.并根据芳香性的平面、电子结构、核独立化学位移(NICS)、以及它们的分子轨道几个标准进行分析.分析的结果指出,2个离域化的σ电子及π电子,分别遵循4n+2电子计算规则,并且呈现出纯σ与π双芳香性.

We extended the aromaticity concept to all-metallic clusters Hf3^2-.The optimized geometries and electronic total energies(including ZPE)of Hf3^2- clusters are investigated at the B3LYP,B3PW91 and MP2 levels.The computed results indicate that clusters Hf3^2-have only one stable structure D3h.The aromatic character of these clusters has been analyzed based on planarity,electronic stability,nuclear independent chemical shift(NICS)values and their molecular orbitals pictures.The detailed Mos analysis further reveals that there are two delocalized σ and π electrons which adhere to the 4n+2 electron counting rule respectively and play an important role in rendering these species the two-fold aromaticity.